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EXECUTIVE SUMMARY (WHAT'S NEW IN 2004) Catch-per-unit-effort trends presented in this report may appear slightly different than trends reported in previous years. Differences in collection methodology among years created the necessity to refine and standardize the data so that only comparable data was included in the catch trend the analysis. We took the following steps to refine the data prior to analysis. 1. Fixed Trip ID's within the GCMRC 14.5 database so that the data for any given of year of Little Colorado River sampling since 1987 could be obtained by the trip ID. (Table 2). 2. Queried out all Lower 1200 meter Little Colorado River sampling by trip ID and verified that each year was accounted for. 3. Added the 2004 Lower 1200 meter data. 4. Removed all D-Hoop nets and Fyke nets from the analysis so that only Gear types, HN, MH, and GFH were included. 5. Standardized effort. Many records were missing effort. In some cases effort could be calculated from start and end times and in other cases effort was extrapolated. In most cases nets were set for either 12 or 24 hours. 6. Queried only data collected during the months of April and May. Some years had extensive effort at other times of the year which biased CPUE trends. We have added length frequency histograms for the most recent 6 years of monitoring for all ofthe native species (Figures 1-3). Although catch is highly influence by runoff from the LCR some ofthe more general trends are evident, such as the large number of age 1 HBC that have been present during the past few years as well as large increase in all size classes of flannelmouth and bluehead suckers. We have also included CPUE trends since monitoring began in 1987 for more size groups of humpback chub (Figure 9). These trends were created using the refined data set described above and confirm the declining trend in adult HBC numbers as seen in mark-recapture population estimates and open population models. The majority ofthe humpback chub recaptured in 2004 were either tagged within the last 3 years or were tagged 9- 15 years ago (Figure 14). This supports ideas that adult chub are not remaining within the Little Colorado River continuously and may only return to the LCR to spawn sporadically. During 2004 we experimented with a solar powered PIT tag antenna to remotely detect tags in moving fish without handling them. A total of 62 unique fish passed through the antenna (Table 9, Appendix-recapture histories). This type of non-intrusive sampling with a remote antenna could be used in conjunction with a temporary weir to answer questions about population closure, spawning and movement patterns of humpback chub in the Little Colorado River. 4